The present invention relates to a reading and printing apparatus or reader-printer for microfilm and the like and more particularly relates to a reader-printer having the functions for directing a light image of information contained on the microfilm selectively onto an observation screen or onto a photosensitive member by scanning for copying thereof.
Generally, in a reader-printer of the above described type, it is necessary to cause reflecting mirrors for projecting the light image onto the observation screen and onto the photosensitive member or photoreceptor selectively to enter or withdraw from the light path through a projecting lens when the projection of the light image is changed over from the observation screen onto the photoreceptor or vice versa, and if the space for such withdrawal is taken into account, the size of the reader-printer itself becomes quite large, thus resulting in some cases in turbulence or blur in the copied images arising from positional deviations and vibrations following advancing and retracting movements of the respective reflecting mirrors. similarly, when the images to be projected onto the screen are large, the light path for the projection onto the screen also becomes large, with consequent increase in the size of the apparatus.
Furthermore, in the reader-printer as described above which is generally a combination of an optical system for selectively directing the image information from a film in an aperture card, etc. onto the observation screeen or photosensitive member, and a copying device for printing, if a photosensitive member of the drum type is employed for slit exposure, it is necessary to provide a scanning device for causing a carrier holding the aperture card to scan in synchronization with the circumferential speed of the photosensitive drum. In the arrangement as described above wherein the carrier is caused to scan, it is necessary to position the carrier so that, with respect to the optical axis of a projecting lamp of the optical system, the central portion of the image is aligned during the functioning as a reader and the edge of the image in the scanning direction is aligned during the functioning as a printer for causing the carrier to start the scanning from such position. For varying the relative position between the optical axis of the optical system and the image in the functioning as the reader and in the starting of the scanning during functioning as the printer, an arrangement for changing-over of the position of the optical system itself or changing-over of the position of the carrier itself can be used, but in the former arrangement, alteration of the optical system, especially alteration of the light path from the projecting lamp thereof to the projecting lens requires special moving means, with consequent complication and increase in size of the reader-printer, while an extra space for scanning the carrier is also required, so that the arrangement is suitable for practical application. Meanwhile, in the latter arrangement in which the carrier is moved to the scanning starting position during functioning as the printer, the driving system such as a return spring or the like normally provided in the scanning device may be utilized as a moving means therefor, and moreover, space for allowing the carrier to scan may be provided for efficient operation, thus bringing about the advantage that the apparatus itself is not unnecessarily complicated or made large. However, even when the latter arrangement as described above is adopted, it is required to position the carrier by forcibly causing the carrier to contact positioning members provided at respective positions for projecting the image onto the observation screen upon termination of the returning of the carrier or at a scanning starting position for scanning and exposing the photoreceptor, and thus, it becomes necessary to consider improvements in durability and accuracy of the arrangement by preventing generation of noises and vibrations by absorption of impacts at the time of the contact between the carrier and the positioning members. Furthermore, since the sizes of the images in the aperture cards are normally different, the sizes of the copied images are not the same even if the projecting magnification of the optical system is constant. Therefore, if the scanning starting position is the same for images of different sizes, time is wasted during the scanning. For eliminating such waste of time, it is also necessary to take into account means for selective positioning of the scanning starting position of the carrier so as to correspond to the sizes of the copied images.
Moreover, in a scanning device to which driving force is normally transmitted from a driving mechanism equipped with a main motor, errors in the revolutions to be transmitted to the scanning device tend to take place due to deviations in the focal length and light path length of the projecting lens or deviations in the processing accuracy of pulleys, gears, etc. for the transmission, and therefore, it is required to correct such errors. Moreover, for eliminating waste of time for scanning, it is necessary to control the distance of the scanning so that it corresponds with the size of the image to be copied instead of making the scanning distance of the carrier constant at all times. Normally, for the detection of the terminating position of the scanning corresponding to the sizes of the copied images, displacement of the carrier during the scanning is directly detected, but in the reader-printer as described in the foregoing, since the original, i.e. the image in the aperture card, is extremely small as compared with originals employed in ordinary copying apparatuses, the scanning distance of the carrier is inevitably reduced, and directly detecting such a short distance, i.e. the small amount of displacement of the carrier, may result in large errors, with fine adjustments of a detector (detecting position) and the like being made extremely difficult.
Furthermore, in the reader-printer and the like as described in the foregoing there is a tendency that the center of the image in the film, the optical axis of the projecting lens and the center of the observation screen are not perfectly aligned, with deviation therebetween being due to errors in the amounts of roll films fed, microfiche films, faulty positioning of the aperture cards, deviations in the film positions in the aperture cards, etc., thus resulting in such inconveniences that the projected image is shifted to one side of the observation screen or part of the projected image is not on the observation screen. Upon occurrence of the deviations as described above, it is necessary to make manual fine adjustments of the positions of the films or aperture cards. However, in an apparatus equipped with an automatic feeding device for automatically feeding the film and stopping a predetermined frame at the projecting position, for effecting the manual feeding and adjustment as described above, it is required that the automatic feeding device and manual feeding device be respectively driven without any adverse effect therebetween, and thus, the apparatus becomes undesirably complicated both in construction ans function. On the other hand, in a reader-printer in which scanning and exposure are effected while the aperture card is moved, since a positioning member for the aperture card is provided in the inner portion of the reader-printer or arranged to be moved together with the aperture card, not only does deviation of the film positions take place, but it is difficult to adjust the positioning member so as to correct for the deviation in the film positions or to deal with aperture cards other than standard cards.